[0001] The present invention relates generally to an adjustable lumbar support for a seat,
such as a vehicle seat. More specifically, the invention relates to a pneumatically
adjustable lumbar support which includes a pneumatic cushion.
[0002] U.S. Patent 3,770,315 to Smittle et al, issued November 6, 1973 shows a selectively
adjustable lumbar support for aircraft seat and the like. Smith et al. discloses an
aircraft seat having an adjustable support in the back opposite the seat occupant's
lumbar region. The adjustable support comprises an impermeable, flexible bag filled
with open-cell, elastically resilient foam, and means for controlling the gas pressure
within the flexible bag. Lumbar support is provided by the combined resilience of
the foam and air pressure within the bag, and control of the air pressure by the seat
occupant enables adjustable control of the degree of support provided the lumbar region
of the back. Pressure above ambient is induced by the load of a seat occupant's back
against the bag and air is permitted to escape by way of a manually operated valve
to select the desired degree of firmness. The bag is provided with excess volume in
order to prevent damage to the seat occupant's back due to explosive expansion in
case of rapid decompression of an aircraft cabin.
[0003] In such a conventional lumbar support, the portion of the seat back opposing the
lumbar vertebra of a passenger may protrude unnaturally, particularly when the pneumatic
bag or cushion is expanded. This may detract from the appearance of the seat. Furthermore,
since the passenger's back is supported at about two points, i.e. upper quarter of
the back and the lumbar vertebra, the passenger is apt to feel fatigue or discomfort
after relative long occupation of the seat.
[0004] Therefore, it is an object of the present invention to provide a pneumatic lumbar
support for a seat capable of forming an appropriately curved surface substantially
along the lumbar vertebra to improve the appearance of the seat and to comfortably
support the passenger's back.
[0005] In order to accomplish the above and other objects, the lumbar support for a seat,
according to the present invention, comprises a pneumatic cushion equipped with a
front-facing, flexible board-like member having sufficient rigidity to maintain a
moderately curved support surface along the passenger's back and sufficient flexibility
to be deformed by expansion and contraction of the pneumatic cushion. The board-like
member is positioned on the front side of the pneumatic cushion to oppose the passenger's
back.
[0006] The invention will be understood more fully from the detailed description given herebelow
and from the accompanying drawings of the preferred embodiment of the present invention,
which, however, should not be taken as limitative to the invention but are for explanation
and elucidation only.
[0007] In the drawings:
Fig. 1 is a perspective view of a seat equipped with the preferred embodiment of a
pneumatic lumbar support according to the present invention;
Fig. 2 is a cross-sectional view of the seat of Fig. 1 showing seat back construction including the lumbar support;
Fig. 3 is a perspective view of a pneumatic cushion utilized in the preferred embodiment
of the pneumatic lumbar support as viewed from the back side;
Fig. 4 is cross-sectional view of a modification of the seat contruction of Fig. 2,
in which the pneumatic cushion'is installed within a cushion pad;
Figs. 5 and.6 are perspective views showing modification of the pneumatic cushion
of Fig. 3.
[0008] Referring now to the drawings, particularly to Fig. 1, there is shown a seat adapted
for use in an automotive vehicle. The seat generally comprises a seat back S and a
seat cushion 5. The seat back S is connected . to the rear end of the seat cushion
5 by means of brackets 10 and 11. The seat back S is further provided with a head
rest 12.
[0009] A pneumatic cushion 2 is provided in the seat back S at the position opposite the
passenger's lumbar vertebra. The pneumatic cushion 2 has a port 2a to be connected
to a pneumatic pump (not shown) to adjust the pneumatic pressure in a pneumatic chamber
2b in order to expand and contract the pneumatic cushion. The adjustment arrangement
for adjusting the pneumatic pressure in the pneumatic cushion has been illustrated
in U.S. Patent 3,326,601 to Vanderbilt et al. issued on June 20, 1967. The disclosure
of U.S. Patent 3,326,601 is incorporated by reference.
[0010] As shown in Fig. 2, the seat back S generally comprises a seat back frame 13, a seat
back support 14, cushion pads 1 and 3, and an outer decorative sheet 4. The seat support
14 is suspended in front of the seat. back frame 13 with a plurality of coil springs
15. The pneumatic cushion 2 is interpositioned between the cushion pads 1 and 3 in
the portion of the seat back S opposing the passenger's lumbar vertebra. The pneumatic
cushion 2 is attached to a board-like member 6 which is sufficiently rigid to maintain
a moderately curved surface conforming to the passenger's lumbar vertebra when the
pneumatic cushion is expanded. The board-like member 6 is positioned in front of the
pneumatic cushion 2 and is attached to the .back surface of the cushion pad 3.
[0011] As shown Fig. 3, the pneumatic cushion 2 is enclosed in an air-tight bag 2c of a
flexible material such as synthetic resin sheet. The port 2a extends from the pneumatic
chamber 2b for communication between the pneumatic chamber and the pneumatic pump
(not shown). The board-like member 6 is bonded or attached to part of one surface
of the pneumatic cushion 2. Preferably, the board-like member is formed from palm
board which is made of fibers of the coconut palm embedded in latex. Furthermore,
in the preferred construction, the board-like member 6 is bonded only to the portion
of the pneumatic cushion 2 which experiences the greatest displacement so that the
board-like member will not be deformed to match the contours of the entire surface
of the pneumatic cushion.
[0012] In . the above-mentioned construction, the pneumatic cushion 2 is pumped up by the
pneumatic pump to deform the portion of the lumbar as illustrated in broken lines
in Fig. 2. Since the board-like member 6 is bonded only to a point B in Fig. 2, it
is free to retain its original shape even though the pneumatic cushion surface may
be more drastically curved. Deformation of the pneumatic cushion 2 causes the board-like
member 6 and the cushion 1 to also deform slightly so that the board-like member 6
will form a gently curved surface as shown in broken lines in Fig. 2. The moderately
curved surface of the board-like member 6 imparted to the seat back will more .comfortably
fit the passenger's back than the pneumatic cushion 2.
[0013] Although the invention has been illustrated in detail with the specific embodiment,
the invention should not be limited to the foregoing embodiment but understood as
including any possible modification.
[0014] For example, the board-like member 6 need not always be a palm board, but rather
can be made from any material which will form a moderate curve when the pneumatic
cushion 2 is pumped up. For example, the board member can be a hard-slab urethane
board, chipped urethane board, coarse blanket and so on. Furthermore, the pneumatic
cushion can be integrally installed in the cushion pad 1 as shown in Fig. 4. Also,
the pneumatic cushion can be made in various different forms, as shown in Figs. 5
and 6 for example. In Fig. 5, the pneumatic cushion 7 has enlarged portions 7a at
either horizontal end and thus a surface curved laterally. This will also cause the
board-like member 6 to curve laterally and thereby to conform more closely.to the
shape of the passenger's back. In Fig. 6, the pneumatic chamber in the pneumatic cushion
8 is partitioned into a plurality of chamber sections 8a, 8b, 8c, 8d, 8e and 8f. The
sections 8a and 8f are thicker than the other sections. On the other hand, the sections
8c and 8d are thinner than the sections 8b and 8e. Thus, similar to the pneumatic
cushion of Fig. 5, the board-like member will be curved laterally.
1. A pneumatic lumbar support for a vehicle seat, comprising a cushion pad in a seat
back of the vehicle seat, a cover surrounding said cushion pad, a pneumatic cushion
expandable and contractable in response to variation of the pneumatic pressure therein,
said pneumatic cushion being disposed inside said cushion pad or between said cushion
pad and said cover at a portion of the seat back opposing the lumbar vertebra of the
occupant, characterized by a board-like member (6) interpositioned at the front facing-side
of said pneumatic cushion (2,7,8) and being sufficiently rigid and flexible to be
deformed by said pneumatic cushion (2,7,8) when expanded to form a surface with a
larger radius of curvature than said pneumatic cushion (2,7,8).
2. A pneumatic lumbar support as set forth in claim 1, characterized in that said
pneumatic cushion (2) and said board-like mamber (6) are fixedly attached at the position
B of said pneumatic cushion (2) which experiences the greatest displacement during
variation of the pneumatic pressure.
3. A pneumatic lumbar support as set forth in claim 1 or 2, characterized in that
said pneumatic cushion (7,8) includes some lateral curvature such that said lumbar
supporting portion of the seat back S fits the occupant's back.
4. A pneumatic lumbar support as set forth in claim 3, characterized in that said
pneumatic cushion (8) has a plurality of pneumatic chambers (8a-8f) partitioned from
each other.
5. A pneumatic lumbar support as set forth in any of the above claims, wherein said
pneumatic cushion (2) is interposed between said cushion pad 1 and said cover 3, characterized
in that said board-like member (6) is positioned between said pneumatic cushion (2)
and said cover (3).
6. A pneumatic lumbar support as set forth in any of the above claims, characterized
in that said board-like member (6) is formed from a palmboard.